1. Field of the Invention
The invention relates to shoes, and can be advantageously utilized in athletic shoes in which a plurality of cushioning elements are provided in a sole assembly of the shoe.
2. Discussion of Background
Shoes having cushioning assemblies are well known in a wide variety of forms. For example, cushioning elements have been provided in the form of projections from a contiguous foam sheet, with the projections having various shapes, including semi-spherical projections, convex projections, barrel-shaped projections, etc. The contiguous sheet cushioning assembly is provided as a midsole or sole insert within the shoe.
U.S. Pat. No. 4,345,387 to Daswick discloses an example of a cushioning assembly in which a sheet of cushioning material includes a plurality of rounded projections extending therefrom, with the projections hollow so that they form air pockets to provide a cushioning effect. However, during athletic activities, different regions of the foot are subjected to (and subject the shoe to) different forces and different concentrations of forces, and it can be difficult to accommodate these variations in an interconnected sheet of cushioning elements. Moreover, the force or impact variations not only vary in different regions of the foot for a given activity, but they also vary for different types of activities, as can the fatiguing of cushioning elements among various activities.
Some efforts have been made to accommodate for the variation in forces applied to different regions of a shoe, including providing projections of a contiguous cushioning assembly which have different sizes. However, the ability to vary the cushioning effect utilizing cushioning element size variation alone is limited. For example, it is difficult to form cushioning elements of different hardnesses or material properties where the cushioning elements are joined or formed as part of a single sheet from which the cushioning elements protrude. Moreover, formation of the cushioning elements as an integrated sheet of cushioning elements imposes limitations upon the shapes, variation of shapes, and/or the orientations of a given shape of cushioning element from a manufacturing standpoint. As a result, it is difficult to manufacture a contiguous cushioning assembly or insert for a shoe having the precisely desired variation in hardness/cushioning and support in order to respond to various forces and impacts applied to the shoe and foot.
In addition to the above problems with contiguous sheet cushioning elements most, if not all, conventional cushioning element designs, particularly those of the contiguous sheet variety, are limited in their ability to dissipate energy or impact forces, since the forces are generally absorbed unidirectionally or, in other words, the cushioning elements must absorb the force in the direction in which it is received. In addition, contiguous sheet cushioning assemblies are limited in their ability to provide cushioning elements of a desired density since, as the density of cushioning elements increases, the contiguous sheet becomes more difficult (or impossible) to manufacture, and/or the quality/integrity of each of the respective cushioning elements can be diminished. The limitation upon the density of the cushioning elements limits their ability to effectively transfer forces laterally, i.e, from the location at which the force is received to adjacent cushioning elements and/or to side surfaces of the shoe. Prior cushioning assemblies have also been disadvantageous in requiring separate and complex midsole assemblies, which then must be joined to the outsole to form the sole assembly of the shoe.
Accordingly, improved shoe assemblies, and particularly athletic shoe cushioning assemblies, are constantly under consideration. Particularly needed is a cushioning assembly in which the properties of various portions of the shoe can be tailored to the requirements of the shoe (or wearer) so that shoes can be provided which can accommodate various forces and force concentrations to which the shoe and feet are subjected for various activities and varying needs of the user.